Vehicle headlamps operate most efficiently when they are aimed properly. Similarly, properly aimed headlamps are not a distraction or nuisance to oncoming motorists. The headlamps are normally set for proper aim or alignment when the vehicle is manufactured. However, through use, accident, or replacement, the headlamps often become misaligned.
With the recent conversion of most headlamps to halogen bulbs, alignment becomes more difficult because the beam or light dispersion differs from that of prior incandescent bulbs which produced a more focused pattern which was easier to align. Most automobile repair shops do not have the appropriate tools or equipment necessary to re-aim a headlamp for optimum performance and efficiency. Moreover, many states no longer require headlamp aiming checks during inspection of motor vehicles. Thus, headlamp aiming has become a random hit or miss proposition with technicians being limited to guesstimating if a headlamp is properly aimed.